(1) Credit may be claimed for published articles and books. The amount of credit so awarded will be determined by the board. Credit may be allowed for published articles and books provided they contribute to the professional competence of the individual. Credit for preparation of such publications may be claimed on a self-declaration basis up to 25 percent of the full basic period requirement. In exceptional circumstances an article(s) or book(s) may be provided to the board with an explanation of the circumstances which would justify a greater credit.